Double Frequency Ripple Suppression Control
for a PV Quasi Z-Source Inverter
V.Vengedesh *
EEE Final year
Dr.Paul’s Engineering College
Villupuram.TN
veludeva214@gmail.com
Karthik.K
Kotasriharireddy
EEE Final year
Dr.Paul’s Engineering College
Villupuram.TN
sriharireddy0906@gmail.com
Birjukumar
EEE Final year
Dr.Paul’s Engineering College
Villupuram.TN
kart4209@gmail.com
EEE Final year
Dr.Paul’s Engineering College
Villupuram.TN
kumarbirju80@gmail.com
Abstract: In single-phase photovoltaic (PV) system, there isdouble -frequency power mismatch
existed between the dc input and ac output. The double -frequency ripple (DFR) energy needs
to be buffered by passive netw ork. Otherwise, the ripple energy will flow into the input side
and adversely affect the PV energy harvest. In a conventional PV system, electrolytic inductors
are usually used for this purpose due to their high inductance. . Ho wever, electrolytic
inductors are considered to be one of the most failure prone components in a PV inverter. In
this paper, a inductance reduction control strategy is proposed to buffer the DFR energy in
single-phase Z-source/quasi-Z-source inverter applications. With-out using any extra hardware
components, the proposed control strategy can significantly reduce theinductance
requirement and achieve low input voltage DFR. In this work, an input current ripples
cancellation technique is presented using a DC-AC coupled quasi-Z-source inverter. The
mathematical derivation is established by considering commercialized E ferrite core. Others
geometries can be used and may be optimized. The validation has been conducted on an
electric traction prototype composed of a PM-motor fed by a quasi-Z-source inverter.
Experimental results are in accordance with simulation ones. The input current is thus
”perfectly” continuous (without high-frequency ripples), hence interest as regards voltage
sources (battery, fuel cell) from a lifetime point of view. Other advantages can be pointed out
in comparison with widely used boost-type architecture. For instance, there is no need to use
additional components in the system as the two inductors exist in the quasi-Z-source
topology:
Keywords: PV Panel, Boost Up Transformer, DC-DC Converter, Inverter, IGBT Switch, Inductor
Capacitance Reduction, Double-Frequency Ripple, Z-Source /Quasi-Z-Source .
1.0 INTRODUCTION
I
n the recent years for the photovoltaic
application the voltage fed z-source inverter
and quasi z-source inverter are considered. This
inverter feature single stage buck boost
transformer ,It is due to shoot through capability.
for the single phase and three phase
applications the z-source inverter and quasi zsource inverter are utilized. The single-phase
ZSI/qZSI can also be connected in cascaded
structure for higher voltage application and
higher performance. In three-phase applications,
the Z-source (ZS)/quasi-Z-source (qZS) network
only needs to be designed to handle the high-
* Corresponding Author
frequency ripples. . The qZSI will be used in this
paper to study the low-frequency ripple issue
and present the proposed control strategy. the
ac-side power contains a dc component plus
and ac ripple component and the dc-side output
power is pure dc ,whose frequency is two times
the grid voltage frequency. The mismatched ac
ripple is termed as double-frequency ripple
(DFR) in this paper. In order to balance the
power mismatch between the dc side and ac
side, the DFR power needs to be buffered by the
passive components, mainly the qZS capacitor
which has higher voltage rating than other
capacitance. The DFR peakpower is the same
as the dc input power, so large capacitance is
needed to buffer this ripple energy. To achieve
high inverter power density with reasonable cost,
electrolytic capacitors are usually selected.
Electrolytic capacitors contain a complex liquid
chemical called electrolyte to achieve high
capacitance and low series resistance. As the
electrolytic capacitors age, the volume of liquid
present decreases due to evaporation and
diffusion. This process is accelerated with higher
temperature, eventually leading to performance
degradation over time Therefore, electrolytic
capacitors are considered to be the weak
component regarding to lifetime, especially
under outdoor operation conditions.However, the
added circuits increase the system cost and
complexity. In a low-frequency harmonic
elimination PWM technique is presented to
minimize the DFR on Z-source capacitors. A 1kW qZSI inverter prototype with the proposed
control strategy is built in the laboratory. The
gallium nitride (GaN) devices are applied in the
inverter to increase the system efficiency at high
switching
frequency.
Finally, experimental
results are provided to verify the effectiveness of
the proposed control system.
the inductor and the input side. This is not
suitable for the PV application, because the
ripple current will decrease the energy harvest
from the PV panels.
2) A Fuel cell Power Conditioning System With
Low-Frequency Ripple-Free Input Current
Using a Control- Oriented Power Pulsation
Decoupling StrategyIn some reported singlephase two-stage system which is composed
of a dc-dc converter and H-bridge inverter,
the dc link capacitance can be significantly
reduced by using dedicated control. However,
the qZSI does not have the dc-dc stage.
3) An optimized switching strategy for a ripplecancelling boost converterInteresting results
are also obtained was where the authors
manage to cancel the input current ripples of
a boost-type converter architecture.Some
disadvantages of this proposal can be
pointed out. For instance, it uses additional
active and passive components and is slightly
dependent on the operating point of the
system
3.0 MATERIALS AND METHODS
In this the materials such as PV panel,
boost converter ,dc-dc converter ,inverter ,IGBT
switches, snubber circuit ,inductance.
This work proposes an inductors coupling
technique.To cancel input current ripples of a
quasi-Z-source inverter without adding any
additional
components.
This
means
the
suppression of input filters that are used.
To protect voltage sources, and
whatever the voltage boost factor value.
this
This work proposes an inductors coupling
technique. To cancel input current ripples of a
quasi-Z-source inverter without adding any
additional
components.
This
means
the
suppression of input filters that are used.To
protect voltage sources, and this whatever the
voltage boost factor value.
4.0 RESULTS AND DISCUSSION
2.0 LITERATURE REVIEW
1) Single-phase Z-Source inverter: analysis and
low-frequency harmonics elimination pulse
width modulation
In
this,
a
low-frequency
harmonic
elimination PWM technique is presented to
minimize the double frequency ripple on Zsource capacitors. However, the method is used
for application with constant voltage input source
anddouble-frequency ripple current is induced in
The basic principle of the proposed
capacitance reductionmethod where C is the
capacitance, E is the ripple energy that is stored
in the capacitor, and vCm ax and vCm in are the
maximum and minimum voltages across the
capacitor. According to (1), there are two ways
to increase E. One is to increase the
capacitance C, and the other way is to increase
the voltage fluctuation acrossthe capacitor.
Instead of increasing the capacitance, the
proposed control system will increase the
voltage fluctuation across the qZS capacitors to
buffer more double-frequency power. A dedicated strategy is needed to impose the DFR on
qZS capacitors while preventing the ripple
photovoltaic systems,” IEEE Trans. Power
Electron., vol. 21, no. 6, pp. 1776–1782,
Nov. 2006.
energy from flowing into the input. In order to
achieve this, a modified modulation strategy and
an input DFR suppression controller are
presented. In the proposed control system, the
shoot-through control lines vp∗ and vn∗ are
modified to a line with double-frequency
component as shown in Fig. 2(b). By doing so,
the dc side and the qZS capacitor DFR can be
decoupled. An input DFR suppression controller
is added in the control system to generate the
double-frequency the detailed control system
diagram of the proposed single-phase qZSI. The
proposed control contains the maximum power
point tracking (MPPT) controller, grid-connected
current controller, qZS capacitor voltage
controller, input DFR suppression controller. The
MPPT controller provides the input voltage
reference vIN ∗. The error between and is
regulated by a PI controller and its output is the
magnitude of the grid current reference. The grid
current igis regulated by controlling the inverter
modulation index m through a proportional
resonant (PR) controller.
[3] D. Cao, S. Jiang, X. Yu, and F. Z. Peng,
“Low-cost semi-Z-source inverter for singlephase photovoltaic systems,” IEEE Trans.
Power Electron., vol. 26, no. 12, pp. 3514–
3523, Dec. 2011.
5.0 CONCLUSION
In our project, a new control strategy is
proposed
to
minimize
the
capacitance
requirement in single-phase qZSI PV system.
Instead of using large capacitance, the qZS
capacitors are imposed with higher doublefrequency voltages to store the doublefrequency ripple energy. In order to prevent the
ripple energy flowing into the input PV side, a
modified modulation and an input DFR
suppression controller are used to decouple the
input voltage ripple from the qZS capacitor DFR.
The small signal model is developed and shows
that the capacitance reduction does not impact
the system stability much. Our expected
experimental results will demonstrate our system
performance.
References
[1] Y. Li, S. Jiang, J. G. Cintron-Rivera, and F.
Z. Peng, “Modeling and control of quasi-zsource inverter for distributed generation
applications,” IEEE Trans. Ind. Electron., vol.
60, no. 4, pp. 1532–1541, Apr. 2013.
[2] Y. Huang, M. Shen, F. Z. Peng, and J.
Wang, “Z -Source inverter for residential
[4] W.Wei, H. Liu, J. Zhang and D. Xu,
“Analysis of power losses in Z-source PV
grid-connected inverter,” in Proc. IEEE 8th
Int. Conf. Power Electron. ECCE Asia, May
30–Jun. 3, 2011, pp. 2588–2592.
[5] T. W. Chun, H. H. Lee, H. G. Kim, and E. C.
Nho, “Power control for a PV generation
system using a single-phase grid-connected
quasi Z-source inverter,” in Proc. IEEE 8th
Int. Conf. Power Electron. ECCE Asia, May
30–Jun. 3, 2011, pp. 889–893.
[6] L. Liu, H. Li, Y. Zhao, X. He, and Z. J. Shen,
“1 MHz cascaded Z-source inverters for
scalable grid-interactive photovoltaic (PV)
applications using GaN device,” in Proc.
IEEE Energy Convers.Congr.Expo., Sep.
17–22
Author’s Biography
Mr. Kota Srihari Reddy is
currently
pursuing
his
Bachelor’s degree in Electrical
and Electronics Engineering
from
Dr.Pauls
Engineering
College,
Anna
University,
Tamilnadu, India. His area of
interest is Power Electronics.
Mr. Vengadesh is currently
pursuing his Bachelor’s degree
in Electrical and Electronics
Engineering
from
Dr.Pauls
Engineering
College,
Anna
University, Tamilnadu, India.
His area of interest is Power
Electronics.
Mr.K.Karthcik
is
currently
pursuing
his
Bachelor’s
degreein
Electrical
and
Electronics Engineering from
Dr.Pauls Engineering College,
AnnaUniversity,
Tamilnadu,
India. His area of interest is
Power Electronics.
Mr.Birju Kumar is currently
pursuing his Bachelor’s degree
in Electrical and Electronics
Engineering
from
Dr.Pauls
Engineering
College,
Anna
University, Tamilnadu, India.
His area of interest is Power
Electronics.
Mr.M.Mani received B.E degree
in Electrical and Electronics
Engineering
in
2004
from
Periyar University, Tamilnadu,
India and M.E degree in Power
Electronics and Drives in 2009
from
Anna
University,
Tamilnadu, India. He is currently Assistant
Professor in the Electrical and Electronics
Department, Dr.Pauls Engineering College,
Tamilnadu, India. His research interests are
including Renewable Energy System, Machine
Design and PWM Inverter.